In a large pot or deep skillet, heat the olive oil over medium heat. Add the chopped onion and sauté for 2-3 minutes until translucent.
Add the minced garlic and red pepper flakes to the onions, cooking for an additional 1-2 minutes until fragrant.
Pour in the chicken or vegetable broth, and bring the mixture to a simmer.
Add the uncooked pasta to the pot, ensuring it is submerged in the broth. Cook the pasta according to package instructions, typically about 8-10 minutes, stirring occasionally.
When the pasta is nearly al dente, add the shrimp and cherry tomatoes to the pot. Cook for an additional 3-5 minutes, or until the shrimp turn pink and opaque.
Stir in the dried oregano, lemon juice, salt, and pepper to taste, mixing well to combine all flavors.
Remove from heat and let it sit for a couple of minutes to thicken up slightly.
Garnish with freshly chopped parsley and serve hot, topped with grated parmesan cheese if desired.